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MASH Crashworthiness of Luminaire Poles

Description:

Crashworthiness of poles propose a unique set of obstacles that previous research projects are not likely to address. Some of these challenges are:

· The breakaway base is typically made by one company. The pole and other associated connection hardware are made by others another.

o This can make it difficult to determine if breakaway hardware would be acceptable with other styles of pole or other hardware and who is responsible for testing of the various configurations.

· Previous testing criteria for poles concentrated on acceptable change in velocity and maximum stub height.

o MASH testing criteria includes new occupant compartment crush criteria, including a maximum of 4 inches of roof crush.

§ Little or no data from previous NCHRP 350 crash testing indicates the extent of roof crush or how existing pole configurations would perform with MASH testing criteria.

· Most prior research on breakaway poles was done in the late 80’s and early 90’s and there have been significant changes to the vehicle fleet.

Research conducted by FHWA set the maximum weight and height of poles and associated hardware. These values combined with the roof crush criteria need to be reevaluated. Currently computer models appear to be overestimating roof crush for signs. Lack of accuracy in computer modeling makes it difficult to use computer modeling to predict likely success in crash testing.

Objective:

This research will look to:

· Using physical testing to determine the maximum pole height and weight including all attachments and hardware that would meet MASH criteria.

· Compare testing results to computer modeling. Focusing on increasing the accuracy of the computer modeling.

· Investigate if adjustments to the 4-Inch tall object on a 5-foot chord is still applicable to current vehicle fleet.

Benefits:

Currently, there are no MASH compliant breakaway poles. There are many barriers to developing breakaway poles to MASH criteria. There are multiple manufacturers involved in a breakaway base/pole installation as well as hundreds of potential pole and hardware configurations currently in use Basic research on pole weight and height is needed to develop hardware.

Traffic, safety, standards engineers, manufacturers and eventually the public would benefit from this research. AASHTO MASH crash test criteria would be validated or modified based on the results of this research. Potential improvements in computer modeling can make it less expensive to obtain MASH compliant breakaway poles.

Related Research:
  1. Rowan NJ, Kanak EW. Impact Behavior of Luminaire Supports. TTI; 1967. Report No.: 75-8.

  2. Martinez JE. An Analytical Solution of the Impact Behavior of Luminaire Support Assemblies. Highway Research Record. 1968;222.

  3. Edward TC, Martinez JE, McFarland W, Ross H. NCHRP Report 77 Development of Design Criteria for Safer Luminaire Supports. NCHRP; 1969. Report No.: 77.

  4. AASHTO. 1975 Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals. 1975.

  5. Nordheim E, Prodoehl RF, Dusel J. Dynamic Tests of Breakaway Lighting Standards Using Small Automobiles. Caltrans; 1975. Report No.: FHWA-RD-76-50-527.

  6. Owings RP, Adair JW, Rudd TJ. Safer Sign and Luminaire Supports Task F - Laboratory Acceptance Testing for Sign and Luminaire Supports Volume 1. FHWA; 1976. Report No.: FHWA-RD-76-32.

  7. Bloom JA, Hinch J. Laboratory Evaluation of Existing Breakaway Structures Volume 3 Test Data. 1979.

  8. Mak K, Mason R. Accident Analysis - Breakaway and Non-Breakaway Poles Including Sign and Light Standards Along Highways Volume II Technical Report. FHWA; 1980. Report No.: DOT-HS-805-605.

  9. Hinch J, Manhard G, Stout D, Owings RP. Laboratory Procedures to Determine the Breakaway Behavior of Luminaire Supports in Mini-Sized Vehicles Collisions Volume 1 R. FHWA; 1987. Report No.: FHWA/RD-86/105.

  10. Hinch J, Manhard G, Stout D, Owings RP. Laboratory Procedures to Determine the Breakaway Behavior of Luminaire Supports in Mini-Sized Vehicles Collisions Volume 2 Technical Report. FHWA; 1987. Report No.: FHWA/RD-86/106.

  11. Hinch J, Manhard G, Stout D, Owings RP. Procedures to Determine the Breakaway Behavior of Luminaire Supports in Mini-Sized Vehicle Collision Volume 3 Foil Operation and Safety Plan. FHWA; 1987. Report No.: FHWA/RD-86/107.

  12. Hansen A. Summary of Luminaire Support Capability Testing. FHWA; 1988. Report No.: FHWA/RD-87/104.

  13. Stoughton RL, Abghari A, Dusel J, Hedgecock J, Glauz D. Vehicle Impact Testing of Lightweight Lighting Standards. Transportation Research Record. 1989;1233.

  14. FHWA. FHWA Memorandum Breakaway Sign and Luminaire Support. 1990.

  15. Pfeifer BG, Holloway J, Faller R, Post ER, Christensen DL. Full-Scale Crash Tests on a Luminaire Support 4-Bolt Slip-Base Design. Transportation Research Record. 1992;1367.

  16. AASHTO. 1994 Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals. 1994.

  17. Vallabhan G, Burkette W. Evaluation of Structural Strength Characteristics of Light Pole Transformer Bases. Texas; 1997. Report No.: TX-970-1416-1R.

  18. AASHTO. AASHTO Standard Specifications for Structural Supports Pages. 2009.

  19. AASHTO. 2009 Manual for Assessing Safety Hardware (MASH)2009.

  20. Rosenbaugh S, Faller R, Lechtenberg K, Bielenberg B, Sicking D, Reid JD. Dynamic Evaluation of New York State’s Aluminum Pedestrian Signal Pole System MwRSF; 2009. Report No.: TRP-03-223-09

  21. AASHTO. 2011 AASHTO Roadside Design Guide 4th Edition. 2011.

  22. AASHTO. 2015 Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals. AASHTO; 2015.

  23. AASHTO. LRFD Specification for Structural Supports for Highway Signs, Luminaires, and Traffic Signals 2015.

Tasks:

This research will provide the following:

  1. Determine maximum height and weight of breakaway poles and hardware that will meet MASH requirements.

a. Physical test data needed to correlate roof crush with pole and hardware height and weight and aid in determining critical pole configurations.

b. This may include dropping poles with associated hardware of varying height and weights onto vehicles as a precursor to full-scale crash testing.

  1. Identify improvements to vehicle computer models to better simulate crash testing roof crush.

  2. Investigate if adjustments to the 4-inch tall object on a 5-foot chord is still applicable to current vehicle fleet.

a. Review procedures used to develop the 4-inch tall on a 5-foot chord criteria.

b. Determine if modification or improvements to the procedure can be implemented.

c. Conduct analysis of procedures with current vehicle fleet.

The research will be presented in the AASHTO Manual for Assessing Safety Hardware, AASHTO Roadside Design Guide, Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals.

Implementation:

The following AASHTO committees would likely be implemented the results: Technical Committee of Roadside Safety, and Highways Subcommittee on Bridges and Structures.

Results could be implemented into revisions or interpretations of the following AASHTO documents: AASHTO Manual for Assessing Safety Hardware, AASHTO Roadside Design Guide, Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals.

Traffic, safety, and standards engineers would be responsible for implementing use of MASH-compliant hardware systems developed as a result the results of this research. Recommendations provided by this research could be implemented in standard drawings and design standards. Also, the following AASHTO documents

Relevance:

Results from this research may help guide futures improvements to MASH, the Roadside Design Guide, and other AASHTO documents.

This relates to TCRS’s Strategic Plan by develop, implement, and maintain evaluation standards to support roadside safety innovation and decision making.

Sponsoring Committee:AKD20, Roadside Safety Design
Research Period:Longer than 36 months
RNS Developer:Erik Emerson, Jennifer Rasmussen, Michael S. Stenko, Akram Abu-Odeh, Eric Lohrey
Source Info:AKD20 Summer Meeting 2020
Date Posted:01/04/2021
Date Modified:02/10/2021
Index Terms:Crashworthiness, Utility poles, Breakaway supports, Crushing, Crash tests,
Cosponsoring Committees: 
Subjects    
Highways
Design
Safety and Human Factors
Bridges and other structures

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